JP2009517713A - Color projector having compact optical integrator and method for projecting image using the color projector - Google Patents

Abstract

  In the color projectors 200, 300, and 400, the light source 220 generates first, second, and third colored light beams. The optical integrators 230, 330, and 430 integrate the first colored light beam, the second colored light beam, and the third colored light beam. The integrated first colored light beam, the second colored light beam, and the third colored light beam are integrated into the first light modulator 252, the second light modulator 254, and the third light, respectively. Modulated by modulator 256 to provide first, second and third colored images. The light combiner 260 combines the first, second, and third colored images to form a combined color image, and the projection lens 180 projects the combined color image. The optical integrators 230, 330, and 430 are polarized beams for increasing an effective integration length of the corresponding colored light beam in at least one optical path of the first, second, and third colored light beams. Splitters 240 and 441 are included.

Description

  The present invention relates to a color projector and a method for projecting a color image, and more particularly, to a color projector using a compact optical integrator to enhance the uniformity of imaging and projected light, and color The present invention relates to a method for projecting an image.

  Color projectors generally have three main components: an illumination system that includes a light source and illumination optics, an image generation system that includes one or more light modulators, and a projection system that includes projection optics. Can be divided into On the other hand, the demand for color projectors that display color images is increasing. This demand has been driven by cost, size and weight reduction, and performance improvement of color projectors.

  One of the stimulating elements in the size, weight and performance of color projectors is the lighting system, in particular the light source. Generally, a color projector uses an ultra high pressure (UHP) mercury lamp as a light source. However, there are practical limitations to creating a small, lightweight, and low power lighting system that includes a UHP light source that can be created.

  Accordingly, it would be desirable to provide a color projector that can use another illumination system that can reduce the overall size and weight of the color projector. It would also be desirable to provide a color projector with a compact and high performance lighting system. Furthermore, it would be desirable to provide a method for projecting an image using such a projector. The present invention is directed to addressing one or more of the problems set forth above.

  In one aspect of the invention, a color projector integrates a light source adapted to generate first, second and third colored light beams, and the first colored light beam; An optical integrator adapted to integrate the second colored light beam and to integrate the third colored light beam; and each of the integrated first, second and third colored light beams. A corresponding first, second and third coloring from a corresponding one of the integrated first, second and third colored light beams adapted to receive a corresponding one of the The first, second and third light modulators adapted to generate an image and the first, second and third colored images are combined to form a composite color image A light combiner adapted to project the combined color image, and the optical integrator comprises at least one of the first, second and third colored light beams A polarizing beam splitter is included in one optical path.

  In another aspect of the invention, a method for projecting an image includes providing first, second, and third colored light beams, integrating the first colored light beams, and second coloring. Integrating a light beam and integrating the third colored light beam; modulating the integrated first light beam, the integrated second light beam, and the integrated third light beam; And generating the corresponding first, second and third colored images, and combining the first, second and third colored images to form a composite color image, Integrating the first colored light beam, integrating the second colored light beam, and integrating the third colored light beam; Comprises providing to the polarization beam splitter at least one of the second and third colored light beams.

  Further and other aspects will become apparent from the description below.

  FIG. 1 illustrates relevant parts of a color projector 100 including an illumination system 110, an image generator 150 and a projection system 180.

  The illumination system 110 includes a light source 120 and an optical integrator 130.

  The light source 120 includes first, second and third light emitting diodes (LEDs) 122, 124 and 126, a collimator 128, and a polarizer 129. Although the embodiment of FIG. 1 includes a pair of first LEDs 122, a pair of second LEDs 124, and a pair of third LEDs 126, in other examples, the light source 120 includes a single first LED 122, a single LED. Only one second LED 124 and a single third LED 126 may be included. The first, second and third LEDs 122, 124 and 126 emit colored light having three different colors (first, second and third colors, respectively). Beneficially, the first, second and third LEDs 122, 124 and 126 emit red light, blue light and green light, respectively. The collimator 128 collects light from the first, second, and third LEDs 122, 124, and 126 and collimates the light into first, second, and third colored light beams. Polarizer 129 linearly polarizes the light into the desired polarization for proper operation of image generator 150.

  On the other hand, the optical integrator 130 includes first, second and third integrating light rods 132, 134 and 136. Beneficially, each integrating light rod 132, 134, 136 is an optical quality glass with a rectangular cross-section. Beneficially, the cross section may have an aspect ratio of 16: 9 or 4: 3. However, the integrating light rods 132, 134, 136 can be made of plastic or any other suitable optically transparent material instead of glass.

  The image generator 150 includes first, second and third light modulators 152, 154 and 156 and a light combiner 160. Beneficially, the first, second and third light modulators 152, 154 and 156 are each a liquid crystal display (LCD) device, in particular a transmissive LCD light modulation panel. The first, second, and third light modulators 152, 154, and 156 each receive corresponding image signals from electronic components (not shown) in the color projector 100. Beneficially, the photosynthesizer 160 has a recombination cube, also known as an X-cube.

  Projection system 180 includes at least one projection lens.

In operation, the first, second, and third LEDs 122, 124, and 126 operate in conjunction with the collimator 128 to generate first, second, and third colored light beams, respectively.
Beneficially, the first, second and third colored light beams are red, green and blue colored light beams. The first, second and third colored light beams are supplied to the light integrator 130, and in particular, supplied to the first, second and third integrating light rods 132, 134 and 136, respectively. The The first, second and third integrating light rods 132, 134 and 136 each integrate, i.e., mix and integrate, the first, second and third colored light beams, respectively. A first colored light beam that is integrated, a second colored light beam that is integrated, and a third colored light beam that is integrated. The first, second, and third light modulators 152, 154, and 156 are integrated first colored light beam, integrated second colored light beam, and integrated third colored light beam, respectively. Receive the corresponding one. The first, second, and third light modulators 152, 154, and 156 also receive corresponding image signals from electronic components (not shown) in the color projector 100, and in response to the corresponding image signals, respectively. Modulating the integrated first colored light beam, the integrated second colored light beam and the integrated third colored light beam, from which the corresponding first, second and third colored light beams are modulated. Generate an image.

  The light combiner 160 combines the first, second, and third colored images and outputs a combined color image to the projection system 180, and the projection system 180 projects the color image.

  In the color projector 100, the light “path” of each colored light beam includes an integrating light rod that “mixes” the colored light and provides a more uniform intensity distribution. Thereby providing uniform illumination of the light modulator (LCD panel). Very importantly, the length of this integrating light rod determines the performance, i.e. the longer the integrating light rod (i.e. the longer the optical path length), The uniformity of the integrated colored light beam is improved. However, long integrating light rods do not fit very well in small, compact, lightweight color projectors. This effect is particularly noticeable in the green channel. Due to the standard photosynthesizer (recombination cube) configuration, the green channel is always in the center (ie, the third colored light beam). As a result, the integrating light rod for the green colored light beam is shorter than the integrating light rod for the red and blue colored light beams. Unfortunately, it is also well known that in white images, the most lumens are in green light. Therefore, non-uniformity is more noticeable in the green channel. In general, it will generally be true that in normal television images, or DVD movies, or just any “normal” video content, the most lumens will be in the green channel.

  FIG. 2 illustrates relevant portions of a color projector 200 that at least partially address these issues. The color projector 200 includes an illumination system 210, an image generator 250, and a projection system 280.

  The illumination system 210 includes a light source 220 and an optical integrator 230. The light source 220 includes first, second and third light emitting diodes (LEDs) 222, 224 and 226, a collimator 228, and a polarizer 229. The embodiment of FIG. 2 includes a pair of first LEDs 222, a pair of second LEDs 224, and a pair of third LEDs 226, but in other examples, the light source 220 includes a single first LED 222, a single LED. Only one second LED 224 and a single third LED 226 may be included, or each may include more than two LEDs 222, 224, 226. The first, second and third LEDs 222, 224 and 226 emit colored light beams having three different colors (first, second and third colors, respectively). Beneficially, the first, second and third LEDs 222, 224 and 226 emit red light, blue light and green light, respectively. A collimator 228 collects light from the first, second and third LEDs 222, 224 and 226 and collimates the light into first, second and third colored light beams. Polarizer 229 linearly polarizes the light into the desired polarization for proper operation of polarizing beam splitter 240 and image generator 250 as described below.

  The optical integrator 230 includes first, second and third integrating light rods 232, 234 and 236. Beneficially, each integrating light rod 232, 234, 236 is an optical quality glass with a square cross-section. However, the integrating light rods 232, 234, 236 can be made of plastic or any other suitable optically transparent material instead of glass.

  However, unlike the color projector 100, in the color projector 200, the optical integrator 230 also includes a polarizing beam splitter 240 in the optical path of the third colored light beam (beneficially a green colored light beam). The length of the third integrating light rod 236 is shorter than the length of the first and second integrating light rods 232 and 234. The general operation of a polarizing beam splitter is well known to those skilled in the art and therefore will not be described herein. The optical integrator 230 further includes first and second quarter wave plates 242, 244 and first and second mirrors 246, 248. The functions of the color projector 200, the polarizing beam splitter 240 in the optical integrator 230, the first and second quarter wave plates 242 and 244, and the first and second mirrors 246 and 248, are described in detail below. explain.

  The image generator 250 includes first, second and third light modulators 252, 254 and 256, and a light combiner 260. Beneficially, the first, second and third light modulators 252, 254 and 256 are each a liquid crystal display (LCD) device, in particular a transmissive LCD light modulation panel. The first, second, and third light modulators 252, 254, and 256 receive corresponding image signals from electronic components (not shown) in the color projector 200, respectively. Beneficially, the photosynthesizer 260 has a recombination cube, also known as an X-cube.

  Projection system 280 includes at least one projection lens.

  In general, the operation of the color projector 200 is the same as the operation of the color projector 100 except for the operation of the optical integrator 230. Therefore, in order to prevent redundancy, only the difference in operation between the color projector 200 and the color projector 100, that is, the operation of the optical integrator 230 will be described here.

  A third colored light beam from a third LED (beneficially a green LED) 226 is provided to the polarizing beam splitter 240 of the optical integrator 230. Because of the polarizer 229 between the collimator 228 and the polarizing beam splitter 240, only light with the correct polarization direction will reach the polarizing beam splitter 240. Polarization beam splitter 240 is arranged such that the third colored light beam is reflected toward one of the side walls, preferably one side wall on the long axis of optical integrator 230. Here, the first quarter-wave plate 242 and the first mirror 246 are arranged. Note that the extraordinary axis of the first quarter wave plate 242 is rotated 45 degrees relative to the polarization direction of the incoming light. The first quarter wave plate 242 is traversed twice, and in combination with the mirror 246, the polarization of the third colored light beam is changed from horizontal to vertical (or vice versa). . On the other hand, the polarization beam splitter 240 is transparent to light in this polarization direction. The same configuration is arranged on the other side wall of the polarizing beam splitter 240, that is, the second quarter-wave plate 244 and the second mirror 248 are arranged. Since the third colored light beam passes through the second quarter wave plate 244, is reflected by the second mirror 248, and again passes through the second quarter wave plate 244, so The polarization direction is reversed again. The light beam again strikes the polarizing beam splitter 240. However, since the polarization is reversed by the second quarter wave plate 244 and the second mirror 248, the polarization beam splitter 240 causes the third colored light beam to travel toward the third light modulator 256. And the third colored light beam is first further integrated by the third integrating light rod 236.

  Accordingly, by providing the polarizing beam splitter 240, the integration length of the third colored light beam (eg, green light beam) is effectively approximately tripled. This sacrifices a few percent loss of intensity due to absorption in the mirror, but without increasing the size of the color projector 200 compared to the color projector 100, one of the green light (which is the most important light). Increase the appearance considerably.

  In addition to (or instead of) placing a polarizing beam splitter in the optical path of the third colored light beam in the optical integrator (eg, in the green channel), the first ( It should be understood that a polarizing beam splitter can be added, for example, in the optical path of a colored light beam and / or a second (eg, blue) colored light beam. Two or more beam splitters can be used for a single color light path. The cost / performance tradeoff will determine whether this is desirable.

  As explained above, a polarizing beam splitter can be incorporated in the optical integrator to achieve improved performance of the color projector without increasing the size. However, in other examples, the size (length) of the color projector may be reduced, as shown below with respect to FIG.

  FIG. 3 illustrates relevant portions of another embodiment 300 of a color projector having an optical integrator 300 that includes a polarizing beam splitter 240. In the color projector 300, the optical integrator 330 does not include the third integrating light rod in the optical path of the third colored light beam, and the length of the first and second integrating light rods 332 and 334 is long. Except for being shortened, it is similar to the color projector 200 and basically performs the same operation. According to this embodiment, the size (length) of the color projector 300 can be reduced as compared with the color projector 100, but the effective integration path of the third colored light beam (for example, the green colored light beam) is Still, it can be made slightly longer than the color projector 100.

  FIG. 4 illustrates relevant portions of another embodiment 400 of a color projector. In general, the configuration and operation of the color projector 400 is similar to the configuration and operation of the optical integrator 430 and the operation of the optical integrator 430, and the first, second and third LEDs 222, 224 and The configuration and operation of the color projector 200 are the same except for the change in the positional rearrangement of H.226. Therefore, in order to prevent redundancy, only the difference in configuration and operation between the color projector 200 and the color projector 400, that is, only the configuration and operation of the optical integrator 430 will be described here.

  The optical integrator 430 includes first and second integrating light rods 432 and 434, first, second and third polarizing beam splitters 441, 443 and 445, and first and second quarters. One-wave plates 442 and 444, first and second mirrors 446 and 448, and first and second optically transparent (eg, glass) members 435 and 437 are included. Beneficially, each integrating light rod 432, 434 is an optical quality glass with a rectangular cross-section.

  The optical integrator 430 operates as follows. A first colored light beam (eg, a red colored light beam) is sequentially reflected by a third polarizing beam splitter 445, passes through a first quarter-wave plate 442, and passes through a first mirror. 446, reflected back through the first quarter wave plate 442, passed through the third polarizing beam splitter 445, passed through the second polarizing beam splitter 443, and the first polarizing beam splitter 441. , Passes through the second quarter wave plate 444, is reflected by the second mirror 448, passes back through the second quarter wave plate 444, and passes through the first polarizing beam splitter 441. Is reflected toward the first light modulator 252. On the other hand, the second colored light beam (for example, the blue colored light beam) is sequentially reflected by the second polarizing beam splitter 443, and is reflected by the third polarizing beam splitter 445 to the second light modulator 254. Reflected towards. In addition, the third colored light beam (for example, the green colored light beam) is reflected by the first polarizing beam splitter 441 and then is directed toward the third light modulator 256 by the second polarizing beam splitter 443. Reflected. A first optically transparent member 435 disposed in an optical path between the first polarizing beam splitter 441 and the second polarizing beam splitter 443; a second polarizing beam splitter 443; A second optically transparent member 437 disposed in the optical path between the polarizing beam splitter 445 and the light beams in the first, second and third colored light beams, which are variously polarized beam splitters. Helps keep you through.

  In the color projector 400, the lengths of the integration paths of the first, second, and third colored light beams are not the same. However, this is not important as long as each of the integration path lengths is sufficient to make the light beam uniform. That is, once the light distribution of the light beam in the optical integrator is uniform, it will remain in the path as it travels any remaining length of the optical integrator.

  Advantageously, the use of the three polarizing beam splitters 441, 443 and 445 in the optical integrator 430 of the color projector 400 and the vertical path provide a much longer path for the three colored light beams than in the color projector 100, Therefore, the uniformity of the light intensity distribution of the integrated colored light beam is significantly increased. This enhances the quality of the image projected by the color projector 400.

  It should be understood that there can be several different arrangements of color and polarization beam splitters, and that the embodiment shown in FIG. 4 and the above embodiments are exemplary in nature.

  While preferred embodiments are disclosed herein, there can be many variations that remain within the concept and scope of the invention. Such variations will become apparent to those skilled in the art after a review of the specification, drawings, and claims of this application. Accordingly, the invention is not limited except as by the spirit and scope of the appended claims.

1 illustrates one embodiment of a color projector. 3 illustrates another embodiment of a color projector. 3 illustrates yet another embodiment of a color projector. Fig. 4 illustrates yet another embodiment of a color projector.

Claims (20)

A color projector,
A light source adapted to generate first, second and third colored light beams;
An optical integrator adapted to integrate the first colored light beam, integrate the second colored light beam, and integrate the third colored light beam;
Each of which is adapted to receive a corresponding one of the integrated first, second and third colored light beams and which is integrated with the first, second and third colored light beams First, second and third light modulators adapted to produce corresponding first, second and third colored images from corresponding ones of
A light combiner adapted to combine the first, second and third colored images to form a composite color image;
A color projector having a projection lens adapted to project the composite color image,
A color projector, wherein the optical integrator includes a polarization beam splitter in an optical path of at least one of the first, second, and third colored light beams.   2. The color projector according to claim 1, wherein the light source includes first, second, and third light emitting diodes that emit the first, second, and third colored light beams, respectively.   The color projector according to claim 1, wherein one of the colored light beams is a green light beam, and the polarization beam splitter of the optical integrator is in an optical path of the green light beam. projector.   The color projector according to claim 1, wherein the polarization beam splitter of the optical integrator is in the shortest optical path of the first, second, and third colored light beams. The color projector according to claim 1, wherein the optical integrator is
A first integrating light rod adapted to integrate the first colored light beam;
A second integrating light rod adapted to integrate the second colored light beam;
A color projector having said polarizing beam splitter adapted to integrate said third colored light beam.   6. The color projector according to claim 5, wherein the optical integrator further includes first and second quarter-wave plates and first and second mirrors.   The color projector according to claim 5, wherein the third colored light beam is a green light beam.   6. The color projector according to claim 5, wherein the optical integrator further includes a third integrating light rod disposed in an optical path of the third colored light beam.   The color projector according to claim 1, wherein the optical integrator further includes a second polarization beam splitter. The color projector according to claim 9,
A third polarizing beam splitter;
A first optically transparent member disposed in an optical path between the first polarizing beam splitter and the second polarizing beam splitter;
A color projector further comprising a second optically transparent member disposed in an optical path between the second polarizing beam splitter and the third polarizing beam splitter.   The color projector according to claim 1, wherein at least two different colored light beams pass through the polarizing beam splitter.   The color projector according to claim 1, wherein the first, second, and third light modulators are all liquid crystal devices. A method of projecting an image,
Providing first, second and third colored light beams;
Integrating the first colored light beam, integrating the second colored light beam, and integrating the third colored light beam;
The integrated first light beam, the integrated second light beam, and the integrated third light beam are modulated to produce corresponding first, second, and third colored images. Steps,
Combining the first, second and third colored images to form a composite color image, comprising:
Integrating the first colored light beam, integrating the second colored light beam, and integrating the third colored light beam includes the first, second, and third colored light beams. Providing at least one of the following to a polarizing beam splitter.   14. The method of claim 13, wherein the first, second, and third colored light beams are provided by first, second, and third light emitting diodes, respectively.   14. The method of claim 13, wherein the at least one colored light beam is a green light beam.   14. The method of claim 13, wherein integrating the first colored light beam comprises passing the first colored light beam through a first integrating light rod; Integrating the second colored light beam comprises passing the second colored light beam through a second integrating light rod, and integrating the third colored light beam comprises the third colored light beam. Passing the colored light beam through the polarizing beam splitter.   The method according to claim 16, wherein the third colored light beam is a green light beam. 17. The method of claim 16, wherein the steps of integrating the third colored light beam are in turn:
Reflecting the third colored light beam from the polarizing beam splitter;
Passing the third colored light beam through a first quarter wave plate;
Reflecting the third colored light beam from a first mirror;
Passing the third colored light beam back through the first quarter wave plate;
Passing the third colored light beam through the polarizing beam splitter;
Passing the third colored light beam through a second quarter wave plate;
Reflecting the third colored light beam by a second mirror;
Passing the third colored light beam back through the second quarter wave plate;
Reflecting the third colored light beam toward a third light modulator by the polarizing beam splitter.   17. The method of claim 16, wherein integrating the third colored light beam further comprises passing the third colored light beam through a third integrating light rod. 14. The method of claim 13, wherein integrating the first colored light beam comprises supplying the first colored light beam to the first polarizing beam splitter, Integrating the colored light beam includes providing the second colored light beam to a second polarizing beam splitter, and integrating the third colored light beam includes the third colored light beam. Supplying to a third polarizing beam splitter.

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